2012 Volume 16 Issue 3 Pages 276-282
Purpose: The purpose of this study was to investigate the influence which posture change of a head has on thyroid cartilage movement during swallowing using ultrasonography (US), and, to examine whether thyroid cartilage movement recorded by US becomes a simple and effective evaluation index of the time of position adjustment of the head.
Subjects and Methods: Subjects were 9 healthy male adults (25.4±5.3 years of age). They sat in a fixed position on a chair with the back and head in contact with the wall. The position of the subjects was changed in two ways: alteration in the mid-position of the head and neck (Mid P), and the maximum extended position of the head (Ext P). The ultrasonography probe was applied to the left side of the thyroid cartilage. The ultrasonography device was adjusted so that the uppermost portion of the thyroid cartilage appeared in the center position of the ultrasonography monitor. The length of time that the thyroid cartilage moved in one cycle of swallowing was divided into three phases: elevation, rest, and descent. The time of each phase was measured and the total time of the movement was determined by the sum of the times of the three phases. The means of three measures for each phase or total time were used data analyses.
Results: We acquired clear images of the thyroid cartilage and its movement by ultrasonography. The means of the elevation and rest times showed no significant difference between the two head positions. The mean of the descent times was 0.73±0.15 sec in Mid P and 0.94±0.15 sec in Ext P, with the latter time being significantly longer than the former (p＜0.05). The mean of the total times was 1.51±0.11 sec and 1.89±0.15 sec in Mid P and Ext P, respectively, with the latter being significantly longer than the former (p＜0.01).
Conclusion: Using the analysis of thyroid cartilage movement during swallowing as depicted by ultrasonography, it became clear that the descent time, as well as the total time of the thyroid cartilage movement in Ext P was longer than those in Mid P. Ultrasonograhy of the thyroid cartilage movement during swallowing may be useful for appropriate positional adjustment of the head during a meal because ultrasonography is easy to use in real time at bed side swallowing evaluation.
